Material for chromatography

ABSTRACT

Granulated products are provided and include carbonaceous particles and a carbonized agent or binder. The agent or binder is preferably a synthetic resin, pitch component, or mixture thereof. Packing materials for packing columns used in chromatographic separations are also provided as are methods of chromatographic separation using the materials. In addition, methods are provided to provide a variety of different types of carbonaceous products. A variety of chemical groups can be, prior to heat-treatment and/or thereafter, attached to the granules to form modified granules.

This application is a divisional of U.S. patent application Ser. No.09/944,064, filed Aug. 31, 2001 now U.S. Pat. No. 6,787,029.

BACKGROUND OF THE INVENTION

The present invention relates to a packing material for chromatographicseparations and to a method of manufacturing the same. Moreparticularly, the present invention relates to a packing material forliquid chromatography produced by mixing a carbon product, such ascarbon black with a synthetic resin and/or a pitch component,granulating the mixture, and heat treating the resultant granules. Thepresent invention also relates to methods of chromatographic separationthat employ the granules.

Conventionally, packing materials for liquid chromatography haveincluded silica gel materials and synthetic resin-based materials.However, problems such as chemical stability, including solubility, haveresulted in silica gel-based materials exhibiting poor durability as apacking material.

In chromatography and other separation methods, there is a certainamount of selectivity that is necessary in order for the stationaryphase to separate the various components in a mixture. For this reason,carbon products, such as carbon black, have not been used as a standardstationary phase in separation systems because carbon is a strongnon-specific adsorbent. This has been disappointing in the past, becausecarbon products, otherwise, would have many advantages over commerciallyavailable adsorbents. For instance, there are no corrosion problems withcarbon products nor are there any swelling problems with carbonproducts. In addition, carbon products can be subjected to largetemperature ranges and/or extreme pressures which would be beneficialfor certain types of adsorptions, such as temperature swings used insome types of chromatography. In addition, with certain separationprocesses used in the production of biopharmaceuticals for clinicalapplications, the sterilization requirements or recommendations providefor the use of hot sodium hydroxide. With such sterilization procedures,the current separation devices such as silica columns, cannot be used.Further, the polymeric columns such as cellulose polymers, arechemically but not physically stable to such sterilization treatments.

U.S. Pat. No. 5,270,280 relates to the use of carbon black packingmaterials for liquid chromatography, wherein the carbon blacks havespecific dimensional ratios, specific particle diameters and surfaceareas, and specific micropore volumes. The patent is incorporated hereinin its entirety by reference. The methods of making the packing materialaccording to U.S. Pat. No. 5,270,280 include granulating a carbonblack-containing mixture and heat-treating the granules at a hightemperature in the range of from 800° C. to about 3000° C., in an inertatmosphere. The high temperature heat-treatment is most likely necessaryto carbonize and graphitize the binder material in order to form agraphitic layer. According to the patent, if the temperature is below800° C., the graphitization of the binder is not sufficient, resultingin the packing material having insufficient strength. While the patentdescribes the packing material as providing improved mechanicaldurability and separating characteristics, a need still exists for animproved liquid chromatography packing material that has improvedmechanical durability and improved separating properties.

It is desired to provide an improved liquid chromatographic packingmaterial and a method of producing such a material which does notrequire a high temperature heat-treatment or graphitization step.

In addition, it is desired to provide a method of chromatographicseparation that provides improved separation of sample components.

SUMMARY OF THE INVENTION

The present invention relates to an improved chromatographic packingmaterial made of carbonaceous particle-containing granules preferablyhaving at least one organic group attached thereto. The granules includecarbonaceous particles and the carbonized product of a carbonizablesynthetic resin, pitch component, or both. Preferred granules includecarbon black particles having attached organic groups and a carbonizedsynthetic resin, pitch component, or both.

The present invention further relates to a process for making thepacking material of the present invention and includes: mixingcarbonaceous particles with at least one synthetic resin, pitchcomponent, or both, and with at least one organic or aqueous solvent, toform a mixture; granulating the mixture to form granules; heating thegranules at a relatively low temperature of from about 400° C. to lessthan 800° C. to carbonize the synthetic resin, pitch component, or both,and to evaporate the solvent. Once formed, the packing material can befurther customized for specific uses by attaching an organic group orgroups to the carbon surface.

The carbonized synthetic resin, pitch component, or both, preferablyacts to strongly bind the carbonaceous particles into a strong granule,very differently than the temporary binding action of pelletizing orbinding agents designed to facilitate ready dispersal of carbon blackparticles from a pelletized carbon black.

The packing materials of the present invention preferably exhibitexcellent mechanical durability and preferably provide improvedseparating abilities in chromatographic separation applications. Thesurface-modified granular packing materials of the present invention areparticularly useful in liquid chromatographic separation applications.

Additional features and advantages of the present invention will be setforth in part in the description that follows, and in part will beapparent from the description, or may be learned by practice of thepresent invention. The objectives and other advantages of the presentinvention will be realized and attained by means of the elements andcombinations particularly pointed out in the description and appendedclaims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide further explanation of the presentinvention, as claimed.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a microphotograph (at 5,000× magnification) of chromatographicpacking materials of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention relates to a chromatographic packing material. Thecarbonaceous particles are preferably bound together with the carbonizedproduct (e.g., binder) of at least one synthetic resin, at least onepitch component, or both.

The carbonaceous particles that can be treated to form the packingmaterial of the present invention are preferably selected from graphitepowder, graphite fibers, carbon fibers, carbon cloth, vitreous carbonproducts, activated carbon products, and carbon black. A preferredcarbonaceous particulate material is carbon black. In addition, thecarbonaceous particles can include, but are not limited to, carbonaerogels, pyrolized ion exchange resins, pyrolized polymer resins, mesocarbon microbeads, pelleted carbon powder, nanotubes, buckey balls,silicon-treated carbon black, silica-coated carbon black, metal-treatedcarbon black, densified carbon black, activated carbon or othercarbonaceous material obtained by the pyrolysis of cellulosic, fuel oil,polymeric, or other precursors and combinations thereof or activatedversions thereof The carbonaceous particles can also include, but arenot limited to, material obtained by the compaction of small carbonparticles and other finely divided forms of carbon as long as thecarbonaceous particles have the ability to adsorb at least one adsorbateand is preferably capable of being chemically modified in accordancewith the present invention. The carbonaceous particles can also be awaste product or by-product of carbonaceous material obtained bypyrolysis.

In addition, the carbonaceous particles can be an aggregate having atleast one carbon phase and at least one silicon-containing speciesphase. The aggregate can be one or more of the aggregates described inU.S. Pat. Nos. 6,008,271; 5,977,213; 5,948,835; 5,919,841; 5,904,762;5,877,238; 5,869,550; 5,863,323; 5,830,930; 5,749,950; 5,622,557; and5,747,562. Furthermore, the aggregates described in WO 98/47971; WO96/37547; and WO 98/13418 can also be used, and each of these patentsand publications is incorporated herein in its entirety by reference.

The carbonaceous particles can be a carbon black which is at leastpartially coated with silica. Examples of such an aggregate aredescribed in U.S. Pat. No. 5,916,934 and WO 98/13428 which areincorporated herein in their entireties by reference.

Besides the above-described aggregates, the carbonaceous particles canalso be an aggregate having at least a carbon phase and ametal-containing species phase as described in PCT Publication WO98/47971 which is incorporated herein in its entirety by reference.

In addition, the aggregates and methods of making multi-phase aggregatesfrom U.S. Pat. Nos. 6,211,279; and 6,057,387; and U.S. patentapplication Ser. No. 09/453,419 can be used, and all of these patentsand application are incorporated herein in their entireties byreference. Additionally, the aggregates of U.S. patent application Ser.No. 60/163,716 having attached polymer groups can be used as can themodified pigments described in U.S. patent application Ser. No.60/178,257, both of which applications are also incorporated herein intheir entireties by reference.

Preferably, the carbonaceous particles are activated carbon or carbonblack capable of adsorbing an adsorbate. Commercial examples of carbonblack include, but are not limited to, Black Pearls® 2000 carbon black,Black Pearls® 430 carbon black, Black Pearls® 900 carbon black, andBlack Pearls® 120 carbon black, all available from Cabot Corporation.Commercial examples of activated carbon include Darco S51, availablefrom Norit; Sorbonorit 3, available from Norit; and BPL activated carbonfrom Calgon. The carbonaceous particles modified by the proceduresdescribed herein may be a microporous or mesoporous activated carbon ingranular or pellet form; a carbon black of different structures influffy or pelleted form; or any other carbonaceous particles whoseapplicability to this invention is apparent to those skilled in the art,such as carbon fibers or carbon cloth. The choice of carbonaceousparticles used eventually depends on a variety of different factors,including the application for which it is intended. Each of these typesof carbonaceous particles has the ability to adsorb at least oneadsorbate. A variety of BET surface areas, micropore volumes, and totalpore volumes are available depending on the desired end use of thecarbonaceous material.

The carbonaceous particles used to form the packing material of thepresent invention preferably comprise particles having an averageparticle diameter of from about 12 to about 40 nanometers (nm) prior togranulation, for example, from about 12 to about 30 nm, and a specificsurface area of from about 50 to about 550 m²/g, for example, from about80 to about 250 m²/g. A preferred particulate material is a carbon blackhaving these properties. The carbonaceous particles used to form themixture preferably have a DBP oil adsorption of from about 50 to about200 ml/100 g, for example, from about 80 to about 150 ml/100 g.

The synthetic resin and/or pitch component preferably attains a firmbonding among the carbonaceous particles and preferably acts as abinder. The synthetic resin and/or pitch component is preferably easilycarbonized by heating. Exemplary synthetic resins that can be usedaccording to the present invention include phenolic resins, furanresins, furfural resins, divinyl benzene resins, urea resins, andmixtures thereof.

If a pitch component is used, it is preferably toluene-soluble orbenzene-soluble. The pitch component is preferably a component ofpetroleum pitches, coal-tar pitches, or liquefied oil from coal.

Both a pitch component and a synthetic resin component can be usedtogether, for example, whereby the pitch component is preferablycombined with the synthetic resin before contacting the carbonaceousparticles. The synthetic resin and pitch component mixture canpreferably be used in an amount of from about 5 parts by weight to about500 parts by weight, for example, from about 40 parts by weight to about300 parts be weight, per 100 parts by weight of carbonaceous particles.

To facilitate homogenization of the carbonaceous particles with thesynthetic resin, pitch component, or both, it is preferable to dispersethe components in a suitable solvent. Preferably, the solvent is aqueousas opposed to non-aqueous or solvent based. Exemplary solvents that canbe used include, but are not limited to, water, alcohols such asmethanol, ethanol, propanol, or the like, organic solvents having anaromatic group such as benzene, toluene, or the like, and generalorganic solvents such as acetone, methylethylketone, or the like. Withwater-compatible synthetic resins, water is a preferred solvent becauseof its ease of handling and processing. Preferably, the solvent is usedin an amount of from about 70 to about 400 parts by weight per 100 partsby weight of the combined carbonaceous particles andsyntheticresin/pitch component. For carbonaceous particles havingparticle diameters of from about 12 to about 30 nm, specific surfaceareas-of from about 80 to about 200 m²/g, and DBP oil adsorptions offrom about 80 to about 200 ml/100 g, about 0.60 part by weight solventcan be used, based on the weight of the carbonaceous particles.

Carbonaceous particles having organic groups attached thereto can in andof themselves be used as readily dispersible carbonaceous particles,even in the absence of a surfactant, and are preferred according to someembodiments of the present invention.

According to a preferred method of the present invention, a process forproducing a material for chromatography is provided and includes mixingabout 100 parts by weight of carbonaceous particles with: from about 10to about 500 parts by weight of at least one of a synthetic resin thatcan be carbonized by heating, and a pitch component; and an organic oraqueous solvent. Preferably, from about 40 to about 250 parts by weightsynthetic resin and/or pitch component are used per 100 parts by weightcarbonaceous particles. The mixture can be formed by any manner used tocombine the components. The mixture can then be granulated to formgranules. The granulation can be accomplished by a wet (emulsion)granulation technique or by a spray drying granulation technique. Any ofthe granulation techniques described in U.S. Pat. No. 5,270,280 can beused. The granules are then subjected to conditions sufficient tocarbonize the synthetic resin and/or pitch component and to evaporatethe solvent. After carbonizing the granules, they can be furthermodified by attaching organic groups to the granules.

The granulating method may be a spray drying granulation method, asubmerged granulating method (an emulsion granulating method), or anyother suitable granulating method that results in spherical granules.According to a preferred spray granulation technique, granules areobtained from spraying a liquid mixture at an elevated temperature andevaporating, if present, the dispersing agent (e.g., surfactant) andsolvent. According to a preferred submerged granulating method, a liquidmixture is added to a heated agent that is not miscible with the liquidmixture. The contact results in the formation of spheres of the liquidmixture.

Carbonization may be performed by a heat-treatment using any temperaturesufficient for carbonization. Preferably, the heat-treatment occurs inan inert gas atmosphere at from about 400° C. to less than 800° C., forexample, at a temperature of from about 400° C. to about 700° C., or400° C. to 790° C. More preferably, the carbonization temperature towhich the granulated carbonaceous particle-containing material isheated, is in the range of from about 400° C. to about 600° C. Dependingupon the particular synthetic resin and pitch components used, theconditions for carbonization can vary, but preferably are sufficient tocarbonize the synthetic resin and/or pitch component withoutcompromising the yield and strength of the packing material. Preferably,heat-treatment occurs under a pressure of from about 1 to about 8kgf/cm² G though other pressures can be used.

The granulated particles obtained are preferably composite bodiescontaining the carbonaceous particles and an agent that uponcarbonization aids in forming a granule of high crush strength. Theagent preferably acts as a binder and includes the carbonized product ofa synthetic resin, pitch component, or synthetic resin/pitch componentmixture. The granules preferably have a L_(min)/L_(max) ratio of fromabout 0.75 to about 1.25, for example, a ratio of from about 0.90 toabout 1.0. A preferred L_(min)/L_(max) ratio is from about 0.95 to about1.0. The granules preferably have a particle diameter of from about 1 toabout 200 μm, a highly porous surface, a specific surface area of fromabout 10 to about 650 m²/g, preferably from about 15 to about 550 m²/g,a total micropore volume of from about 0.01 to about 2.0 ml/g,preferably 0.3 to about 2.0 ml/g, and a V_(0.5)/V_(1.0) ratio of about0.4 or smaller, preferably 0.2 or smaller, wherein V_(0.5) is the gasadsorption volume at a relative pressure P/P₀ of 0.5 and V_(1.0) is thenitrogen gas adsorption volume at a relative pressure P/P₀ of about 1.0at nitrogen gas adsorption isotherm. The particles preferably have aparticle size of from about 2 to about 5 microns, and other ranges belowand above this range can be made.

The granules can be surface modified by attaching (e.g., covalentlybonding) organic groups to the surface. The organic group is preferablyat least one C₁–C₁₀₀ alkyl group and/or at least one aromatic group, analiphatic group, a cyclic organic group, or an organic compound havingan aliphatic portion and a cyclic portion. Preferably, the organic groupis directly attached to the granules. A preferred set of organic groupswhich may be attached to the carbonaceous material, such as carbonblack-containing granules, are organic groups substituted with an ionicor an ionizable group as a functional group. The ionic group maypreferably be an anionic group or a cationic group and the ionizablegroup may form an anion or a cation. Examples of organic groups aredescribed in U.S. patent application Ser. No. 09/654,182 and itscontinuation in part filed Aug. 31, 2001 both incorporated in theirentirety by reference herein.

Preferably, the organic group contains an aromatic group such as aphenyl or a napthyl group and a quaternary ammonium or a quaternaryphosphonium group. The aromatic group is preferably directly attached tothe carbonaceous particle-containing granule.

In one embodiment, the carbonizable binder or carbonizable syntheticresin or carbon izable pitch component are attached onto carbonaceousparticles to form the granulated product of the present invention.

A combination of different organic groups is also possible. Forinstance, it is within the bounds of the present invention to attachmore than one type of organic group to the same granule or use acombination of granules, wherein some of the granules have been modifiedwith one organic group and another portion of the granules has beenmodified with a different organic group. Varying degrees of modificationare also possible, such as low weight percent or surface areamodification, or a high weight percent or surface area modification.Also, mixtures of modified carbonaceous granules and unmodifiedcarbonaceous granules can be used.

Preferably, the modified carbonaceous granules of the present invention,especially when the attached organic group is a phenyl or naphthyl grouphaving substituents like sulfonic acid, carboxylic acid, or quaternaryammonium or salts thereof, can be directly analogous to polymeric ionexchange resins. These types of carbonaceous granules of the presentinvention can have one or more of the following properties as comparedto conventional polymeric ion exchangers:

a) higher temperature stability;

b) greater resistance to swelling; and

c) greater mechanical strength without adversely affecting uptakekinetics.

Furthermore, the modified carbonaceous granules of the presentinvention, besides being used as adsorbents, can also be used inseparations ranging from water treatment to metals separation/recovery,ion exchange, catalysis, and the like. An additional advantage of anadsorbent possessing exchangeable groups as described above is that itconfers on the granules the ability to be further surface modified usingion exchange procedures.

The granules of the present invention can be used in a number ofapplications, for example, as a stationary phase for chromatographicseparations. Typically, a chromatographic system contains a mobilephase, a stationary phase, a pumping system, and a detector. Generally,the stationary phase contains insoluble particles which are preferablyspherical and/or preferably range in size from about 2 microns to about300 microns, more preferably from about 2 to about 5 microns. The choiceof these particles depends on the physical, chemical, and/or biologicalinteractions that need to be exploited by the separation. Conventionalstationary phases, such as silica, agarose, polystyrene-divinylbenzene,polyacrylamide, dextrin, hydroxyapatite, cross-linked polysaccharides,and polymethacrylates are functionalized with certain groups in order toaccomplish the selective separation of particular chemical compoundsfrom a mixture. The precise functional groups that accomplish thisdesired specification are set forth, for instance, in Garcia, Bonen etal., “Bioseparation Process Science,” Blackwell Science (1999),incorporated herein in its entirety by reference (hereinafter “Garcia etal.”).

Another form of separation is electrophoresis which uses an appliedelectric field to produce directed movement of charged molecules. Theprocess is similar to chromatographic methods in that a fixed barrierphase or stationary phase is used to facilitate separation. In thepresent invention, electrophoresis can be accomplished by using astationary phase which contains the carbonaceous materials of thepresent invention.

Similarly, magnetic separations, such as magnetic bioseparations, can beaccomplished using the carbonaceous materials of the present inventionas the stationary phase.

In addition, membrane separations, such as reverse osmosis, can beaccomplished by forming the membrane such that it contains carbonaceousmaterials. The membrane can be formed by dispersing the carbonaceousmaterial in a polymer and casting the polymer mixture to form amembrane.

Generally, any separation technique which involves the use of astationary phase can be improved by the present invention. Inparticular, the stationary phase can be or can contain the carbonaceousgranules of the present invention. Upon knowing the desired chemicalcompound or species to be separated, the carbonaceous granules can betailored to be selective to the targeted chemical species by attachingan organic group or organic groups onto the carbonaceous granules tosuit the separation needed. Since many functional groups are known tocause particular selectivity in separations, these groups can beattached onto the carbonaceous granules to form the modifiedcarbonaceous granules of the present invention and achieve the desiredselectivity for separation processes.

In one embodiment, an adsorbent composition of the present inventioncontains modified carbonaceous granules capable of adsorbing anadsorbate wherein at least one organic group is attached to thecarbonaceous granules.

As a separate embodiment, the present invention further relates to agranulated carbonaceous product which contains carbonaceous particlesand at least one binder which can be carbonizable. The granulatedcarbonaceous product in this embodiment is produced by the process ofmixing the carbonaceous particles with at least one binder andpreferably an aqueous solvent or nonaqueous solvent. The mixture is thengranulated to form granules and then the granules are heated at atemperature below the temperature to carbonize the binder that ispresent. Preferably, the granules are heated at a temperature of fromabout 150° C. to about 250° C. In this process, the uncarbonizedparticles that are formed contain a cured/crosslinked polymer binderwhich is present on the granules and are useful in such applications asadsorption and chromatography.

As indicated above, once the desired separation technique is chosen andthe particular chemical species preferably known, a particularfunctional group or multiple functional groups can be chosen to beattached onto the carbonaceous material in order to accomplish theselectivity needed to conduct the separation process. For instance, asset forth in Garcia et al., heparin is used in the separation oflipoproteins, accordingly, heparin can be attached onto carbonaceousmaterial in order to accomplish the desired separation. Similarly, whencationic exchange processes are needed, a sulfonic acid, for instance,can be attached on a carbonaceous material and when anionic exchangesare needed, a quaternary amine can be attached onto the carbonaceousmaterial. Thus, with the present invention, and the knowledge possessedby one skilled in the art, separation techniques can be conducted usingmodified carbonaceous material to achieve the selectivity desired. Thus,the present invention provides a carbonaceous material which isresistant to corrosion, swelling, and/or extreme temperatures andpressures, but also provides the desired selectivity. In essence, thepresent invention gives the separation field the best of both worlds,namely, selectivity combined with a resilient stationary phase.

The granules of the present invention can preferably be used as apacking material or stationary phase material for chromatography. Forexample, a chromatographic column, such as a liquid chromatographiccolumn, is packed with at least the packing material of the presentinvention. Then, a sample containing two or more components to beseparated is passed, flowed, or otherwise forced through the packedcolumn. Due to the independent affinities of the sample components, andthe retention properties of the packing material with respect to theindividual sample components, chemical separation of the components isachieved as the sample passes through the packed column. The packingmaterial is also useful in gas chromatographic, high performance liquidchromatographic, solid phase extraction, and other chromatographicseparation techniques.

The present invention will be further clarified by the followingexamples, which are intended to be purely exemplary of the presentinvention.

EXAMPLE 1 Preparation of Carbonized Porous Particles (SP-1)

600 g of Vulcan-6™ carbon black were placed inside a pin-mixer. 520 gdeionized water and 180 g of Rutgers-Plenco Resin 12868 were blendedtogether. The mixture was subsequently injected into the pin mixer whileit was running at 100 rpm. After the end of the addition of the liquidphase, the speed of the mixer was increased to 1000 rpm and held at thatspeed for 1 minute. The particles were then discharged from the mixerand dried at 180° C. overnight in order to both remove the excess waterand cure the phenolic resin. The particles were then classified byscreening. The fraction held between the 120 mesh and 325 mesh screenswith particles sizes ranging between 45 and 125 microns was separated.This fraction was then placed in a tube furnace and ramped to 650° C. in4 hours and then held at 650° C. for an additional hour under nitrogen.These particles (SP-1) were found to have a BET N₂ surface area of 138m²/g and a t-surface area of 61.5 m²/g.

EXAMPLE 2 Preparation of Surface Modified Carbonized Porous Particles(SP-2)

0.76 g of sulfanilic acid were mixed with 100 ml of deionized water andsubsequently heated to 60° C. 10 g of the SP-1 particles were added tothe mixture and stirred for 5 minutes. Subsequently, 1.5 g of a 20%solution of NaNO₂ in water were added to the mixture to initiate thetreatment reaction. The mixture was reacted at 60° C. for 1 hour andthen left to cool down to room temperature. The surface modifiedparticles (SP-2) were then filtered out of the reaction medium, washedwith a 1% NaOH solution, water, and ethanol and soxhlet extracted for 12hours in ethanol. The efficiency of the surface modification is shown bythe increase in the sulfur content of the particles after surfacemodification. The sulfur content of the starting particles SP-1 was 0.9wt % and the sulfur content of the particles after surface modificationwas 1.38%. The increase in sulfur content is due to the attachment ofbenzenesulfonate groups to the surface of the particles.

EXAMPLE 3 Preparation of Polymer Bound Porous Carbon Based Particles(SP-3)

7.6 liters of a Cabojet-300™ aqueous dispersion of benzoic acid modifiedcarbon black were placed in a holding tank. 166.7 g of DynachemPhenalloy 2175 phenolic resin were mixed in. The mixture was spray driedat 110 ml/min through a 2-fluid nozzle. The dry particles werecollected, and subsequently cured at 180° C. for 4 hours under nitrogen.The resulting particles SP-3 had a BET N₂ surface area of 126.8 m²/g anda t-surface area of 106.2 m²/g.

EXAMPLE 4 Preparation of Benzenesulfonic Acid Surface Modified PolymerBound Porous Carbon Based Particles (SP-4)

1.384 g of sulfanilic acid were mixed with 50 ml of deionized water in abeaker and heated to 60° C. 5 g of SP-3 particles were added to themixture. 2.76 g of a 20% solution of sodium nitrite in water were addedslowly, and the mixture was left to react for 90 minutes. The reactionmixture was filtered and the particles were reslurried and washed with a1% NaOH solution in water. The particles were refiltered and washed withdeionized water, and subsequently washed with ethanol andtetrahydrofuran. The particles were soxhlet extracted in ethanolovernight. The starting sulfur content of the particles was 0.39 wt %.After the surface modification the sulfur content was 1.39 wt %indicating the attachment of benzenesulfonic groups.

EXAMPLE 5 Preparation of Porous Carbon Particles (SP-5)

80 g of particles SP-3 were heated under nitrogen in a tube furmace to700° C. and held at that temperature for 2 hours. The particles werethen cooled to room temperature. A SEM picture of these particles isshown in FIG. 1.

EXAMPLE 6 Preparation of Benzenesulfonic Acid Surface Modified PorousCarbon Particles (SP-6)

1.384 g of sulfanilic acid were mixed with 30 ml of deionized water in abeaker and heated to 60° C. 5 g of SP-5 particles were added to themixture. 2.76 g of a 20% solution of sodium nitrite in water were addedslowly and the mixture was left to react for 90 minutes. The reactionmixture was filtered and the particles were reslurried and washed with a1% NaOH solution in water. The particles were refiltered and washed withdeionized water, and subsequently washed with ethanol. The particleswere soxhlet extracted in ethanol overnight. The starting sulfur contentof the particles was 0.36 wt %. After the surface modification thesulfur content was 1.79 wt % indicating the attachment ofbenzenesulfonic groups.

EXAMPLE 7 Preparation of Octadecylphenyl Surface Modified Porous CarbonParticles (SP-7)

5.07 g of 4-octadecylaniline were mixed with 22 ml of deionized water,50 g of ethanol, and 6.17 g of a 30% aqueous solution of HNO₃ in abeaker and heated to 50° C. 15 g of particles (made in a similar manneras in Example 5, except heated under nitrogen in a tube furnace to 900°C.) were added to the mixture. 5.07 g of a 20% solution of sodiumnitrite in water were added slowly and the mixture was left to react for90 minutes. The reaction mixture was filtered and the particles werereslurried and washed with ethanol. The particles were refiltered andwashed with a sodium hydroxide solution, tetrahydrofuran and ethanol.The particles were first soxhlet extracted in ethanol overnight and thenextracted in a Dionex ASE-300 extractor with ethanol and a 50/50ethanol/tetrahydrofuran mixture and left to dry. After the surfacemodification the volatile content of the particles was 7.59 wt %indicating the attachment of octadecylphenyl groups.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the present specification andpractice of the present invention disclosed herein. It is intended thatthe present specification be considered as exemplary only with a truescope and spirit of the invention being indicated by the followingclaims and equivalents thereof.

1. A granulated carbonaceous product comprising carbonaceous particlesand at least one uncarbonized binder, produced by the process of: mixingthe carbonaceous particles with at least one binder and at least onesolvent to form a mixture; granulating said mixture to form granules;and heating said granules at a temperature below the carbonaceoustemperature of the binder to form said granulated carbonaceous product.